What happened
On 22 June 2016, at approximately 09:40 local time, an airfield maintenance vehicle, identified by the callsign Rover 32, entered a restricted area at Changi Airport. The vehicle, operated by an employee of an airport maintenance service provider, was conducting a routine inspection of taxiway pavement and markings. While navigating the junction of Taxiway V1 and W1, the driver crossed the runway holding position without authorization.
The vehicle moved approximately 60 meters past the holding position, coming within 30 meters of the edge of Runway 20R. At the same time, a B767 was on its final approach to the same runway. The intrusion triggered a microwave barrier detector within the Airfield Ground Lighting Control and Monitoring System, alerting the Runway 1 Controller. Controllers immediately ordered the vehicle to vacate the runway. Once the vehicle had cleared the area, the controller cleared the arriving aircraft to land, and the B7 .67 landed safely. There were no injuries and no damage to the aircraft.
The investigation
Investigators examined the driver's actions and the operational environment. The driver, a highly experienced Category 1 Airfield Driving Permit holder, reported that he was focused on identifying pavement defects and deteriorating markings. This intense focus caused him to overlook the stop bar lights, runway guard lights, and the painted instruction markings on the taxiway pavement.
Technical reviews of the Airfield Ground Lighting Control and Monitoring System (AGLCMS) confirmed that the microwave barrier detector (MBD) functioned correctly, providing a proactive warning to the tower. CCTV footage and air traffic control transcripts were used to verify the vehicle's precise location and the sequence of communications.
Findings
- The primary cause of the incursion was attentional resource competition, as the driver was simultaneously tasked with driving, communicating with the tower, monitoring aircraft movements, and inspecting the pavement.
- The driver's concentration on identifying pavement defects led to a loss of situational awareness regarding runway boundaries.
- The presence of fading taxiway markings in the area may have contributed to the difficulty in identifying the holding position.
- The automated runway incursion warning system successfully detected the unauthorized movement and enabled a timely response by air traffic controllers.